1. Technical Field
Embodiments relate to the forming of control circuits for capacitive elements powered with an A.C. power supply voltage. Embodiments more specifically relate to a capacitive power supply voltage for an electronic device having at least two operating modes requiring different supply powers.
2. Discussion of the Related Art
Capacitive elements, which are generally controlled from an A.C. power supply source, are used in electronic motors, electronic lamps, or mere capacitors. For the two first mentioned load types, the capacitive element is generally placed at the secondary of a diode bridge. As to A.C. capacitors, they are series-connected with the A.C. voltage source, often including a series resistor. Such capacitors are often used for capacitive power supply circuits, which are one of the different solutions for supplying power to a load from an A.C. power supply voltage originating, for example, from the mains (220 volts or 110 volts). The power is generally provided across a low-voltage capacitor (for example, from a few volts to a few tens of volts).
Many electronic devices require at least two operating modes requiring different supply powers. For example, many electronic devices have a stand-by mode, with a decreased power consumption with respect to an active mode. It is then desired to avoid useless power consumption by the power supply circuit during periods when the supplied device is not active.
It would be desirable to have a capacitive power supply circuit of simple design, with at least two operating modes capable of providing different supply powers.
More generally, it would be desirable to improve the control of a switch in series with an A.C. powered capacitive element.